As a known facsimile apparatus connectable with a data processing terminal, such as a personal computer, there is a facsimile apparatus connected with the terminal through a two-way parallel port interface (compliant with IEEE 1284), e.g., Centronics or the like, or a Universal Serial Bus (USB) interface, as disclosed in Japanese Patent Application Laid-Open No. 7-288625.
In an image processing system constructed with the aforementioned facsimile apparatus and a data processing terminal, as a connection form between the facsimile apparatus and data processing terminal, a single logical interface is assigned to a single physical interface.
Furthermore, a main control unit and a printing unit included inside the facsimile apparatus are connected through one-way parallel communication and a two-way serial interface.
Meanwhile, simultaneous operation of functions, such as a printer, a scanner, a digital camera, a card reader/writer, a facsimile communication and the like, can easily be realized by adopting a USB to a physical interface between an external processing apparatus and facsimile apparatus and providing a plurality of logical channels (USB composite device) compliant with the USB standard.
Furthermore, by adopting a USB to a physical interface between the main control unit of the facsimile apparatus and a sub control unit of a data processing unit/processor provided for the printer, scanner, digital camera, card reader/writer and the like, a construction having no physical interface other than the USB interface can be realized.
However, in the foregoing conventional image processing system, in which the main control unit is connected with the sub control unit of the data processing unit/processor through the USB interface, in order to simplify the control and improve a throughput, a status (status data) generated by the sub control unit is notified to an external processing apparatus without being changed by the main control unit.
Therefore, data managed by the main control unit cannot be notified to the external processing apparatus.